How It All Goes Down
So there's this guy named Gabriel Oak and he sounds like a pretty solid dude (hence the whole "Oak" thing). One day, he sees a proud and beautiful young woman named Bathsheba and decides he wants to marry her. The problem is that Bathsheba thinks she's too good for him and turns him down. Worse yet, Oak loses his livelihood when one of his dogs chases all his sheep off a cliff. Things aren't looking great for the guy.
After wandering the countryside looking for a job, Oak arrives in a town called Weatherbury and gets himself a job as a shepherd. And who should happen to be his new boss but his old flame Bathsheba, who has inherited the farm after her uncle's recent death. Uh oh.
Meanwhile, a wealthy old farmer in the area named Boldwood decides that he'd like to marry Bathsheba, too. And she even gives Boldwood a half-promise to say yes, even though she doesn't love him. Things look like they might wrap up nicely at this point.
But nope. Not so fast. Enter a cocky, handsome young man named Sergeant Troy. He rolls into Weatherbury and sweeps Bathsheba off her feet. The two of them get married quickly, which breaks the hearts of both Boldwood and Gabriel Oak. As you might expect, Troy is a total jerk to Bathsheba after they're married. What's even worse, though, is that Troy used to be engaged to one of Bathsheba's servants—Fanny Robin—and he has left her (and their child) to die in the streets. When Bathsheba finds this out, her heart totally breaks.
It's around this time that Troy realizes he's a bad dude, so he just does everyone a favor by faking his death and disappearing for a year. When life turns out to be really hard without his wife's money, though, he comes skulking back to Weatherbury to claim his fortune. During his absence, Boldwood has pestered Bathsheba into marrying him. On the night Boldwood hopes to announce the engagement, though, Troy shows up to steal Bathsheba away for a second time.
Boldwood snaps and blows the dude away with a shotgun. Shortly afterwards, Boldwood turns himself in at a nearby police station. He's sentenced to be executed, but gets pardoned at the last minute because everyone thinks he's insane. Meanwhile, Gabriel Oak tells Bathsheba that he'll be leaving for America soon. She begs him to stay, and he agrees to… if the two of them can get married. She agrees and they get married shortly after.
Now if Bathsheba had just agreed to marry Gabriel Oak the first time he asked, things would have been a lot tidier. Troy wouldn't have been blown to smithereens and Boldwood would still be hanging around.
Oh, well. It was way more dramatic and juicy this way, and at least there's a (sorta?) happy ending?